The present invention relates to a braking device for an elevator with an elevator car and a counterweight, which are movable along guide rails in an elevator shaft, wherein the braking device is arranged at the elevator car or at the counterweight and in the case of excess speed stops the elevator car or the counterweight at the guide rails by means of spring elements and brake chocks.
There is shown in the U.S. Pat. No. 5,782,319 a braking device for an elevator, which stops the elevator car in the case of emergency. The elevator car drives, by means of an endless cable, a rotating speed limiter, which blocks in the case of a specific excess speed of the elevator car. The blocked speed limiter also blocks the endless cable, but the elevator car moves further downwardly, wherein the blocked endless cable, which is connected with a release lever mechanism of the braking device, trips the braking device. In that case two guided chocks of the braking device are pushed upwardly. The braking force is generated by friction between the chocks and the guide rail of the elevator car. The braking force is on the one hand dependent on the friction of the chocks on the guide rail and on the other hand dependent on a C-shaped compact spring packet at the ends of which are provided guides for the chocks.
A disadvantage of this known device is that the spring packet and the guides are cast from one piece. The spring packet unit has to be manufactured in accordance with the respective braking force to be exerted, which increases the cost of the braking device.
The present invention concerns a braking device for attachment to one of an elevator car and a counterweight that are movable along guide rails in an elevator shaft, wherein the braking device is actuated to engage a guide rail in the case of excess speed. The braking device includes: a housing; a pair of brake chocks mounted on the housing and movable from a disengaged position to a guide rail engaging position; and at least one spring packet mounted on the housing and having opposed ends connected to associated ones of the brake chocks, the at least one spring packet being of modular construction having lamellae selected to produce a predetermined braking force. The braking device has each end of the spring packet detachably connected to the associated brake chock by a spring bracket. The braking device also can include at least one adjusting packet mounted on the housing and having opposed ends connected to an associated one of the brake chocks.
The advantages achieved by the braking device according to the present invention are essentially that a simple construction of the braking device is possible. The braking device consists of only a few different components. Further, it is advantageous that the braking device is adaptable, with the same components, to different braking forces. The braking device is thus usable, without great expense, for elevator cars or counterweights with different masses to be braked. Moreover, the braking device according to the present invention offers the possibility of fine adjustment with respect to the braking force. The spring elements consist of lamellae producible in a simple manner. A greater or lesser number of lamellae can be used in accordance with the respective braking force required.